1. Field of the Invention
The present invention relates to a pneumatic tire suitable for being used in four-wheeled vehicles.
In particular, the present invention relates to a high performance tire such as, for example, a tire designed for high-powered cars or, more generally, a tire intended for applications involving high operating speeds and/or extreme driving conditions.
In more details, the present invention relates to a high performance (HP) or ultra high performance (UHP) tire as well as to a tire suitable for being employed in sporting contests such as track motor races. Preferably, the tire according to the invention is of the type with a markedly flattened section.
More in particular, the present invention concerns an improved belt structure of a pneumatic tire for four-wheeled vehicles.
2. Description of the Related Art
A pneumatic tire generally comprises: a torodial carcass structure comprising at least one carcass ply; a tread band in a position radially external to the carcass structure; a belt structure interposed between the carcass structure and the tread band; a pair of sidewalls applied to the carcass structure in axially opposite positions. The ends of the at least one carcass ply are associated to respective annular reinforcing elements so as to form tire beads, which secure the tire to a wheel rim.
Several belt structures are known in the art of tires for motor vehicles.
EP 0 477 771 B1 discloses a three-belt tire having at least one carcass ply, a tread, a pair of sidewalls, a pair of beads and a belt package located between the tread and the carcass ply. The belt package has three radially arranged plies. First and third plies of the belt package include a plurality of substantially parallel extending polymeric monofilament reinforcing members disposed at a first angle relative to the equatorial plane in the range of about +15 to +20 degrees. A second ply of the belt package is located between the first and third plies and includes a plurality of substantially parallel extending metallic reinforcing members disposed at a second angle in the range of about −15 to −25 degrees relative to the equatorial plane. The second ply is centered relative to the equatorial plane and has an axial width. The first and third plies are centered relative to the equatorial plane and have respective axial widths which are substantially equal to each other and being greater than the axial width of said second ply. Axial edge portions of the first and third plies contact each other.
EP 0 531 136 B1 discloses a high performance pneumatic radial tire including a tread surface formed with a plurality of circumferential grooves, a radial carcass, a belt composed of two belt layers of metal cords, an additional reinforcing layer arranged on a radially outer side of the belt and at an axially central area of the tread, and at least two additional auxiliary layers arranged at each of widthwise opposite side portions of the tread and composed of organic fiber cords. The additional reinforcing layer is composed of cords crossing the metal cords in the belt layer adjacent thereto and inclined with respect to the tire-circumferential direction, and has a width less than the minimum width of the belt but greater than a distance between the circumferential grooves located at widthwise outermost sides of the tread, respectively.
EP 1 057 659 A2 discloses a pneumatic radial tire for passenger car comprising a carcass of a radial structure toroidally extending between a pair of bead cores and comprised of at least one rubberized carcass ply containing organic fiber cords therein, and a belt reinforcing a crown portion of the carcass and comprised of plural belt layers, wherein at least one carcass ply has a cut-out zone in its crown portion and a carcass supporting layer is arranged adjacent to the cut-out zone.
EP 1 071 567 B1 discloses a pneumatic tire comprising a pair of substantially parallel annular beads, at least one reinforced carcass ply wrapped around the pair of beads, a folded belt structure comprising at least one folded belt and at least one cut belt and an overlay disposed over the at least one carcass ply, tread rubber disposed over the folded belt structure, and sidewalls disposed between the beads and the tread rubber. In the illustrated embodiment, the overlay substantially covers edges of the cut belt and is adjacent to the cut belt, and folded edges of the folded belt are folded over edges of the at least one cut belt and the overlay. The folded belt may be reinforced with filaments or cords selected from the group consisting of fiberglass, aramid, carbon fibers, nylon, rayon, polyester, polyol, and mixtures thereof, and the cut belt may be reinforced with filaments or cords selected from the group consisting of steel, fiberglass, aramid, carbon fibers, nylon, rayon, polyester, polyol, and mixtures thereof. The overlay is reinforced with filaments or cords selected from the group consisting of fiberglass, aramid, carbon fibers, nylon, polyester, polyol, and mixtures thereof.